Low divergence single-mode surface-emitting concentric-circular-grating terahertz quantum cascade lasers

We report the design, fabrication and experimental characterization of surface-emitting terahertz (THz) frequency quantum cascade lasers (QCLs) with distributed feedback concentric-circular-gratings. Single-mode operation is achieved at 3.73 THz with a side-mode suppression ratio as high as ~30 dB....

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Published inOptics express Vol. 21; no. 26; pp. 31872 - 31882
Main Authors Liang, Guozhen, Liang, Houkun, Zhang, Ying, Li, Lianhe, Davies, A Giles, Linfield, Edmund, Yu, Siu Fung, Liu, Hui Chun, Wang, Qi Jie
Format Journal Article
LanguageEnglish
Published United States 30.12.2013
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Summary:We report the design, fabrication and experimental characterization of surface-emitting terahertz (THz) frequency quantum cascade lasers (QCLs) with distributed feedback concentric-circular-gratings. Single-mode operation is achieved at 3.73 THz with a side-mode suppression ratio as high as ~30 dB. The device emits ~5 times the power of a ridge laser of similar dimensions, with little degradation in the maximum operation temperature. Two lobes are observed in the far-field emission pattern, each of which has a divergence angle as narrow as ~13.5° × 7°. We demonstrate that deformation of the device boundary, caused by anisotropic wet chemical etching is the cause of this double-lobed profile, rather than the expected ring-shaped pattern.
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ISSN:1094-4087
1094-4087
DOI:10.1364/OE.21.031872